The aim of the proposed research is to determine the hormonal and growth promoting factors which stimulate the growth and biochemical function of the human and calf fetal adrenal, liver, lung and intestine. Specifically we are examining the role of steroid and protein hormones in the stimulation of the synthesis of heme and fetal hemoglobin in fetal liver and we are trying to isolate factors (small proteins) which are erythropoietic other than erythropoietin. We are investigatng the synthesis and metabolism of pressor amines, the prostaglandins and ACTH in human and calf fetal lung in vitro and are studying the role of these hormones in the development of the lung and the synthesis of surfactant. Studies are also in progress to determine the role of hormones and "messengers" in the growth and steroidogenesis of the human and calf fetal adrenal maintained in monolayer culture. In addition, we are studying the binding and role of hormones in the development of the fetal small intestine. In these studies we will determine the cell types which bind the hormones and correlate this with the enzyme induced in the fetal small intestine.